All large commercial aircraft have provisions for escape lines for emergency egress from the flight deck. This normally consists of a rope or a strap that is secured to the aircraft, and extends to the ground through an opened flight deck window.
All areas of an airplane are investigated during the design phase to determine any and all places where a weight savings may be possible. Even though a weight savings found in a particular area is a small amount, it is still important when all such areas are added together. It was found that an escape line could be made that saves weight over presently used lines and in addition proves a much easier line to use.